Merge bitcoin/bitcoin#34982: kernel: Remove NONNULL annotation from destroy method

7560854 kernel: Remove NONNULL annotation from destroy method (Alexander Wiederin)

Pull request description:

  Follow-up to bitcoin/bitcoin#33796 (comment)

  ### Summary
  This PR removes the `BITCOINKERNEL_ARG_NONNULL` annotation from the `btck_block_validation_state_destroy` method in the Kernel API.

  ### Motivation
  No other *_destroy function in the Kernel API carries the NONNULL annotation. Following the convention set by free(), destroy functions should accept null pointers.

  ### Usage:
  Before:
  ```c
  btck_BlockValidationState* state = NULL;
  btck_block_validation_state_destroy(state); // violates nonnull contract
  ```

  After:
  ```c
  btck_BlockValidationState* state = NULL;
  btck_block_validation_state_destroy(state); // well-defined
  ```

ACKs for top commit:
  yuvicc:
    lgtm! ACK 7560854
  kevkevinpal:
    ACK [7560854](bitcoin/bitcoin@7560854)
  achow101:
    ACK 7560854
  janb84:
    ACK 7560854
  theStack:
    ACK 7560854
  w0xlt:
    ACK 7560854
  stickies-v:
    ACK 7560854

Tree-SHA512: 9577098940f49b8f7fd1fb20afe750e9eaaf9d90d25ec3c4f423de223a1fbd0bca6d520061f576eb3923f18e1f2744b3f60d0d0715dfa3832fea83cb538170c2

Author: achow101

src/kernel/bitcoinkernel.h

@@ -1344,7 +1344,7 @@ BITCOINKERNEL_API btck_BlockValidationState* BITCOINKERNEL_WARN_UNUSED_RESULT bt
  * Destroy the btck_BlockValidationState.
  */
 BITCOINKERNEL_API void btck_block_validation_state_destroy(
-    btck_BlockValidationState* block_validation_state) BITCOINKERNEL_ARG_NONNULL(1);
+    btck_BlockValidationState* block_validation_state);
 
 ///@}